Automatic switch for ultra high frequency



Feb. S, 1947. E. c. oKREss M5962 AUTOMATIC SWITCH FOR ULTRA HIGHFREQUENCY Filed oct. 1e, 1942 l Ecs/VER INVENTOR 12 14 Eg 4f 'E c.@Kee-5s Wre- Gs/Emmz BY AM m ATTORNEY atenter Feb. i8,

D STTES 'ENE apron/merc swrrcn ron ULTRA inea FREQUENCY ApplicationGctober 16, 1942,Serial No'. '462;261

This invention relates to electricity of ultrahigh frequency, and moreparticularly, to an automatic switch for controlling the ow of suchenergy in a wave guide.

The principal object of my invention, generally considered, is animproved automatic ultra-high frequency switch of the type generallydesignated as a TR box, whereby such an instrument is adapted to be puttogether by welding certain parts. l

Another object of my invention is to construct a TR box with anannularly corrugated flexible metal diaphragm wall carrying an electrodemovable by means of an adjusting cap or drum head, to flex the diaphragmwall for tuning the cavity, and simultaneously vary the position of theelectrode carried thereby with respect to an associated electrode on axed wall of said cavity.

Another object of my invention is to construct an automatic switch, ofthe type designated as a TR box, in such a manner that parts may be puttogether by welding, thereby' substan-l tially eliminating the use ofglass and reducing the amount of solder used in its construction.

Other objects and advantages of theinvention, relating to theparticulararrangement and construction of the various parts, will becomeapparent as the description proceeds.

Referring to the drawing:

Fig. l is an axial vertical sectional view, after assembly and Welding,of a Wave guide and associated TR bo-x embodying my invention.

Fig. 2 is a plan of the combined structure shown in Fig. 1.

Fig. 3 is a horizontal axial sectional view on the line III- III of Fig.l, in the direction of the arrows.

Fig. 4. is a horizontal sectional view o-n the line .IV- 1V of Fig. 1,in the direction of the arrows.

Fig. 5 is an enlarged fragmentary view corresponding t0 a portion ofFig. 1, before the welding is elected. f

Fig. 6 is a View corresponding to Fig. 5 but showing a modiiication.

Fig. '7 is an elevational view of the switch of my invention andmechanism normally associated t-herewith.

In the Okress et al. application, Serial No. 451,356, led July 17, 1942,and owned by the assignee of the present application, there is describedand claimed an automatic switch for controlling the flow of ultra-highfrequency electricity in a wave guide to thereby protect associatedapparatus; The automatic switcher TR `box of said applicationcomprisesmeans for tuni Claims. (Cl. 1178-44) ing the'box cavity andadjusting the spacing of spark gap electrodes. The maintenance or" thebox cavity in an evacuated condition includes the use of glass-to-metalseals.

In accordance with the present invention, the construction of such aswitch or TR boxis improved by the substantial elimination ofglassto-metal seals and the employment instead of welded connections,such connections being sufficiently removed and electrically isolatedfrom .first .considering the diagrammatic showing YFig..', the referencecharacter li designates a wave generator for producing energy ofxadesired ultra-high frequency which is transmitted along a metal Waveguide l2, which in the present embodiment is of hollow rectangular crosssection, to an antenna I3, which is shown as a .parabolic device fordirecting a beam in a desired direction toward an object. The inventionis to be used With ultra-high frequency radio waves which may beprojected and reflected in substantially the same manner as light Waves.

' Accordingly the projected wave energy may be directed toward someobject, reflected' therefrom, and on its return course intercepted bythe same antenna which concentrates and causes it to reenter the guidei2 and travel therein and through a branch tubeV i4 to excite a receiverit. bviously the returning wave energy will be very weak compared to thetransmitted energy and a TR box i6 is, therefore, interposed in thebranch tube M to check the flow o-f any high-powered energy and yetpermit the receiver to be actuated by the vrelatively weak energy of 'areturning sign311.

The switch or TR box of the present invention comprises a cylindricalbody il of conductive material', preferably metal such as Kovan whichmay be welded. The body -i'l intersects the conductive, preferably metalwave guide branch It, as shown most clearly in Figs. 1 to 5, inclusive,and is united thereto, as by means ci solder it, This cylindrical memberalso carries quarter wavelength conductive cylindrical, preferablymetal, sections i9' and" 2i, each having inner' outstanding annularportions 22 andlv united tothel inner surface of the cylindrical memberI1, or formed integral therewith. The mode of' connection may besoldering if not formed integral. This means that the cylindrical memberI1 carries a pair of coaxial cylindrical portions, the free edges ofwhich extend outwardly away from one another and the inner edges ofwhich are connected to said cylindrical portion in line with the upperand lower walls of the wave guide I4, as shown most clearly in Fig. 1. l

The cylindrical portion I1 also carries windows 24 and 25 of suitabledielectric material such as No-loss glass which serves to pass themicro-wave energy in the guide I4 through the TR box I8. Said windowsare suitably dimensioned, both as to diameter and thickness and with dueconsideration to their dielectric constant, to introduce a minimum ofdisturbance and still give suicient coupling between the TR box cavityand the wave guide. These windows are shown convex outwardly in order tobetter withstand the outside pressure when the box cavity is evacuated,desirably generally circular, and disposed with their centers on theaxis of the Wave guide I4. They are desirably as small as practicablefor obtaining the desired energy transfer without undue lessening of thesurface continuityv of the resonator volume of the box. These windowsare made vacuum tight as by sealing in place in the cylindrical memberI1.

In the present embodiment, Vtuning of the resonator chamber of the TR1box I6 is effected by making the upper wall of said chamber 26 as aflexible conductive or metal diaphragm 21, desirably provided withconcentric annular corrugations, as shown most clearly in Figs. 1 and 4.To the central portion of the diaphragm 21 is secured an adjustableelectrode 28 provided with a threaded stem 29 outstanding therefrom, andcarried by the hub portion 3l of an adjusting drum head, cap or nutmember 32 threadably engaging the cylindrical member I1, as indicated at33. The threads on the electrode extension and cylindrical member I 1,if both right handed, for example, are necessarily of different pitch inorder to provide for adjustment'of the electrode 28 and diaphragm 21 byturning the head 32', the peripheral portion of which is desirablyknurled, as indicated at 34. From a practical standpoint it ispreferable to have thepitch of the threads on the extension 29 greaterthan that of the threads 33. i 1

The bottom wall 35 of the resonant cavity 26 is desirably rigid andcarries a hollow electrode 36, the lower portion of which may be closedby a block of material 31, such as glass, carrying a probe 38 one end ofwhich is impregnated with a salt of radium or other radio-activematerial 39, for inducing the generation of photo-electrons to decreasethe breakdown potential between the electrodes 28 and 36. Otherkeepalive means may be substituted for the radio-v active probe.

The ilexible wall 21 and the relatively rigid wall 3.5 are carried byhollow cylindrical members 4I and 42, of Kovar or other weldableconductive material, provided with outstanding annular flanges 43 and 44respectively welded to the outer edge portions of the cylindricalinember I1, as indicated at 45 and 46. The outstanding anges 43 and 44may initially have annular corrugations or bosses 51 extending towardthe adjacent edges of the cylindrical member I1 to facilitate theformation of welds therebetween, as illustrated in Fig. 5. By virtue ofhaving these welds disposed at a relatively great distance from the waveguide I4 and with what amount to filters or choke plates therebetween,there is no danger of any undesired action, such as spark over, adjacentthe joints, as might be the case if said joints were disposed close toor not electrically isolated from, the resonant cavity dened by thecylindrical member I1 and the portions 21 and 35.

The sections I9 and 2i both have lengths corresponding to a quarter wavewhereby a high impedance is induced at the openings 41 and 48, as theimpedance of the spaces 49 and 5i) is equal to where Q is the meritfactor of said spaces and Zo the characteristic impedance, which is highbecause Q is high. This high impedance at 41 and 48 is transformed,through the characteristic impedance of the spaces 5I and 52, to a verylow impedance at the annular gaps 53 and 54, causing the same to actelectrically shorted although mechanically no metallic contact exists.The Q of the resonant cavity 26 is somewhat reduced by thisconstruction, but not seriously.

After connecting the cylindrical portion I1 with the associatedcylindrical portions I9 and 2l to the Wave guide i4, and welding theflanges 43 and 44 to the cylindrical portion I1, to assemble the wallportions 21 and 35 and their associated electrodes therewith, theadjusting drum or nut 34 may be applied in any desired manner, as byturning in place on the ends of the associated threads respectivelycarried by the cylindrical portion I1 and the electrode extension 29,starting with the electrodes 28 and 38 either touching or veryclosetogether so that upon turning on the adjusting drum said electrodesare gradually separated until in the position illustrated in Fig. 1where they are in approximately the correct adjustment, with theflexible wall 21 disposed substantially parallel to the xed wall 35.

As'an alternative the drum may be formed in two parts adjustablyconnected as by screws 55. after the parts have been individually turnedin place on the cooperating threads 33 and 29. This latter constructionavoids the necessity of initially flexing the diaphragm 21.

Any desired means may be provided for evacuating the chamber 26, such asan exhaust tube 56 extending from the glass block 31.

Referring now to the embodiment of Ymy invention illustrated in Fig.I 6,the cylindrical member I1a is there shown with an outstanding peripheralannular flange 58, and the cylindrical member 42a is likewise providedwith an annu lar flange 44@1 corrugated as indicated at 51a for unitingwith the flange 58 as an alternative to the welded connection 46 of therst embodiment. A similar welded construction may be substituted for thewelds 45 of the iirst embodiment.

From the foregoing disclosure, it willbe seen that I have provided forthe use of welds to hasten and cheapen the manufacture of "TRY boxes.Such welds are separated from the resonant box cavity by parts ofsufiicient impedance, so that the welded joints are isolated andprevented from interfering with the resonant characteristics.

In operation, when high power tends to pass down the wave guide I4toward the receiver I5,

the potential diierence developed between uthe electrodes 28 and 35,after proper tuning of the cavity 26 and adjustment between theelectrodes, the breakdown potential therebetween being lowered by thekeep alive probe 38, is sufficient to cause sparking between saidelectrodes, Iresulting in a large impedance mismatch which acts as anexcellent reflector of energy attempting to get through to sensitivereceiving apparatus l5.

When, however, a signal is being received, the

tersecting said guide structure, hollow inner metal` members havinginner electrode-carrying closure portions cooperating with said outermetal member to define a resonant cavity and terminating in flangesextending outwardly and welded to said metal member, and lter meansdisposed between said outer and inner members and extending from theguide structure toward the welds for electrically isolating the latterfrom said resonator cavity.

2. In combination, an elongated hollow conductive structure adapted tofunction as a guide for electricity of ultra-high frequency, and aresonator comprising a hollow outer metal member intersecting said guidestructure and enclosing coaxial spark-gap electrodes, each electrodebeing carried by a wall of said resonator, each wall being bordered byportions extending outwardly from its periphery and terminating in aflange overlying and welded to an end portion of said outer metalmember.

3. In combination with an elongated hollow conductive structure adaptedto function as a guide for electricity of ultra-high frequency, aresonator comprising a hollow outer'inetal member intersecting saidguide structure and enclosing coaxial spark-gap electrodes, eachelectrode being carried by a wall of said resonator, each wall beingbordered by portions extending outwardly from its periphery andterminating in an outwardly extending flange welded to an end portion ofsaid outer metal member, and means for tuning said resonator andadjusting the distance between said electrodes.

4. In combination with an elongated hollow conductive structure adaptedto function as a guide for electricity of ultra-high frequency, aresonator comprising a hollow outer metal member intersecting said guidestructure and enclosing coaxial spark-gap electrodes, a iiexiblediaphragm carrying one of said electrodes, a fixed wall portion carryingthe other of said electrodes, and hollow metal portions extending awayfrom one another and the peripheries of said diaphragm and xed wallportions and each terminating in an outwardly extending flange welded toend portions of said outer metal member.

5. In combination with an elongated hollow conductive structure adaptedto function as a guide for electricity of ultra-high frequency, aresonator comprising a hollow outer metal member intersecting said guidestructure and enclosing coaxial spark-gap electrodes, each electrodebeing carried by a wall of said resonator, each wall being bordered byportions extending outwardly from its periphery and terminating in aflange overlying and welded to an end portion of said outer metalmember, one of said electrodes being hollow, and a probe disposedcoaxially within said electrode and insulated therefrom, and meansassociated with said probe for lowering the breakdown potential betweensaid electrodes.

6. In' combination with an elongated hollow conductive structure adaptedto function as a guide for electricity of ultra-high frequency, meansintersecting said guide structure andv defining therewith a resonatorchamber enclosing coaxial spark-gap electrodes, each el-ectrode beingcarried by a wall 0f said resonator coplanar with a wall of said guideexterior of said chamber, and means providing for exhausting saidresonator chamber and making it vacuumtight.

'7. In combination with an elongated hollow conductive structure adaptedto function as a guide for electricity of ultra-high frequency, meanskintersecting said guide structure and defining a resonator chamberenclosing coaxial spark-gap electrodes, each electrode being carried bya wall of said resonator, one of said electrodes being hollow, and meanscommunicating with rthe interior of said hollow electrode for exhaustingsaid resonator chamber.

8. In combination with an elongated hollow conductive structure adaptedto function as a guide for electricity of ultra-high frequency, aresonator comprising a hollow outer metal member intersecting said guidestructure and enclosing coaxial spark-gap electrodes, each electrodebeing carried by a wall of said resonator, each wall being bordered byportions extending outwardly from its periphery and terminating in aflange overlying and welded to .an end portion of said outer metalmember, and filter means dis-- posed between the cavity of saidresonator and said welds for isolating the latter and preventing themfrom interfering with the characteristics of the former.

9. In combination with an elongated hollow conductive structure adaptedto function as a guide for electricity of ultra-high frequency, aresonator comprising a hollow generally cylindrical outer metal memberintersecting said guide structure and enclosing coaxial spark-gapelectrodes, means associated with one of said electrodes for loweringthe breakdown potential, a flexible diaphragm carrying one of saidelectrodes, a fixed wall portion carrying the other of said electrodes,hollow cylindrical portions extending outwardly from the periphery ofsaid diaphragm and fixed wall portions, each terminating in an annularfiange extending outwardly and welded to an outer portion of said outermetal member, filter plates disposed between said guide structure andwelds for isolating the latter from the resonant cavity defined by theguide structure and cylindrical portion, and means for tuning saidresonator and adjusting the distance between said electrodes comprisinga drum head threadably mounted on said outer metal portion andthreadably receiving an extension of the electrode carried by saidflexible metal member, the threaded portions on the lcylindrical memberand electrode extensions differing in pitch whereby turning of said drumhead adjusts the position of the flexible metal wall portion andelectrode carried thereby with respect to the other electrode.

10. A TR box comprising a hollow body resonator with a cavity'denedby'portions of the walls of a hollow conductive structure adapted tofunction as a guide for electricity of ultra-high frequency and `t1,hollow outer metal member intersecting said guide structure, withlateral eX- tensions from walls of said guide structure welded to endportions of said outer metal member at points remote from the resonatorcavity.

il. In combination with an elongated hollow conductive structure adaptedto function as a guide for electricity of ultra-high frequencyfa, TR boXintersecting said guide structure and comprising a hollow bodyresonator, opposed spark-gap electrodes enclosed thereby, and means forflexing a wall of said resonator which is generally coplanar with a,wall of vsaid guide to simultaneously tune the same and; adjust the gapbetween said electrodes.

12. A TR box comprising a hollow body resonator, opposed spark-gapelectrodes enclosed thereby, means for flexing a wall of said resonatorto simultaneously tune the same and adjust the gap between saidelectrodes, and means associated with one of said electrodes forlowering the breakdown potential therebetween.

13. A TR box comprising a hollow body resonator, opposed spark-gapelectrodes enclosed thereby, meansassociated with one of said eleotrodesfor exhausting the resonator cavity, and means for exing a wall of saidresonator to simultaneously tune the same and adjust the gap betweensaid electrodes.

VV8 t 14. A "TR box comprising a hollow body res#4 onator, opposedspark-gap electrodes enclosed thereby, means for flexing a wall of saidresonator to simultaneously tune the same and adjust the gap betweensaid electrodes, Welds connecting the resonator body to an associatedwave guide, and means for electrically isolating said welds from saidwave guide to eliminate their inuence on the characteristics of theresonator cavity. v

ERNEST C. OKRESS.

REFERENCES CITED The following references are of record in the ie ofthis patent:

UNITED STATES PATENTS Number Name Date 2,1062770 Southworth Feb. 1, 19382259,690 Hansen Oct. 21, 1941 2,108,640 Bieling Feb. 15, 1938 2,263,648Salzberg Nov. 25, 1941 2,190,668 Llewellyn Feb. 20, 1940 2,242,275Varian May 20, 1941 1,304,868 Franklin May 27, 1919 FOREIGN PATENTSNumber Country Date 277,666 German Sept. 3, 1914

